Unfilled conductive blends of polyamide-6,6 and poly(phenylene ether) have long been used for exterior automotive parts such as fenders, mirror shells, and fuel filler doors due to their advantages including on-line painting capability, weight reduction (versus steel) for better fuel efficiency, dent resistance, and impact resistance. To date, the blends of polyamide-6,6 and poly(phenylene ether) have not been suitable for other exterior automotive components such as side sill panels and door panels because of difficulties formulating blends that simultaneously meet requirements for heat resistance, stiffness, electrical conductive, and coefficient of thermal expansion.
Coefficient of thermal expansion can be reduced by adding fillers such as glass fiber, talc, or mica. However, the addition of these materials tends to compromise impact strength. Electrical conductivity can be improved by adding electrically conductive carbon agents such as conductive carbon black (CCB), single-wall nanotubes (SWNT), or multi-wall nanotubes (MWNT), but their addition tends to increase cost, reduce impact strength, and reduce melt flow. European Patent Application Publication No. 2 192 156 A1 of Koevoets et al. describes compositions including specific amounts of polyphenylene ether, polyamide, filler, and multi-wall nanotubes (“carbon fibrils”). The compositions exemplified in the Koevoets application perform adequately for many uses, but for certain automotive uses, including side sill panels and door panels, there is a need for compositions that exhibit increased electrical conductivity, stiffness, and melt flow while substantially maintaining the heat resistance, and coefficient of thermal expansion.